1 attogram (ag) = 0.000000000001 milligram (mg).
Attogram (ag) is a unit of Weight used in Metric system.
Milligram (mg) is a unit of Weight used in Metric system.
Attograms also can be marked as Attogrammes (alternative British English spelling in UK). Milligrams also can be marked as Milligrammes (alternative British English spelling in UK).